/*
 * Copyright 2014 The Netty Project
 *
 * The Netty Project licenses this file to you under the Apache License,
 * version 2.0 (the "License"); you may not use this file except in compliance
 * with the License. You may obtain a copy of the License at:
 *
 *   http://www.apache.org/licenses/LICENSE-2.0
 *
 * Unless required by applicable law or agreed to in writing, software
 * distributed under the License is distributed on an "AS IS" BASIS, WITHOUT
 * WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied. See the
 * License for the specific language governing permissions and limitations
 * under the License.
 */

package io.netty.util.concurrent;

import java.util.LinkedHashSet;
import java.util.Set;

/**
 * @param <V> the type of value returned by the {@link Future}
 * @param <F> the type of {@link Future}
 * @deprecated Use {@link PromiseCombiner}
 *
 * {@link GenericFutureListener} implementation which consolidates multiple {@link Future}s into
 * one, by listening to individual {@link Future}s and producing an aggregated result
 * (success/failure) when all {@link Future}s have completed.
 */
@Deprecated
public class PromiseAggregator<V, F extends Future<V>> implements GenericFutureListener<F> {

  private final Promise<?> aggregatePromise;
  private final boolean failPending;
  private Set<Promise<V>> pendingPromises;

  /**
   * Creates a new instance.
   *
   * @param aggregatePromise the {@link Promise} to notify
   * @param failPending {@code true} to fail pending promises, false to leave them unaffected
   */
  public PromiseAggregator(Promise<Void> aggregatePromise, boolean failPending) {
    if (aggregatePromise == null) {
      throw new NullPointerException("aggregatePromise");
    }
    this.aggregatePromise = aggregatePromise;
    this.failPending = failPending;
  }

  /**
   * See {@link PromiseAggregator#PromiseAggregator(Promise, boolean)}. Defaults {@code failPending}
   * to true.
   */
  public PromiseAggregator(Promise<Void> aggregatePromise) {
    this(aggregatePromise, true);
  }

  /**
   * Add the given {@link Promise}s to the aggregator.
   */
  @SafeVarargs
  public final PromiseAggregator<V, F> add(Promise<V>... promises) {
    if (promises == null) {
      throw new NullPointerException("promises");
    }
    if (promises.length == 0) {
      return this;
    }
    synchronized (this) {
      if (pendingPromises == null) {
        int size;
        if (promises.length > 1) {
          size = promises.length;
        } else {
          size = 2;
        }
        pendingPromises = new LinkedHashSet<Promise<V>>(size);
      }
      for (Promise<V> p : promises) {
        if (p == null) {
          continue;
        }
        pendingPromises.add(p);
        p.addListener(this);
      }
    }
    return this;
  }

  @Override
  public synchronized void operationComplete(F future) throws Exception {
    if (pendingPromises == null) {
      aggregatePromise.setSuccess(null);
    } else {
      pendingPromises.remove(future);
      if (!future.isSuccess()) {
        Throwable cause = future.cause();
        aggregatePromise.setFailure(cause);
        if (failPending) {
          for (Promise<V> pendingFuture : pendingPromises) {
            pendingFuture.setFailure(cause);
          }
        }
      } else {
        if (pendingPromises.isEmpty()) {
          aggregatePromise.setSuccess(null);
        }
      }
    }
  }

}
